Originally published as Genetics Published Articles Ahead of Print on April 16, 2005.

Genetics, Vol. 170, 749-766, June 2005, Copyright © 2005
doi:10.1534/genetics.105.040667

A Screen for Genes Regulating the Wingless Gradient in Drosophila Embryos

Sabrina C. Desbordes1, Dhianjali Chandraratna and Bénédicte Sanson2

Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom

2 Corresponding author: Department of Genetics, University of Cambridge, Downing St., Cambridge CB2 3EH, United Kingdom.
E-mail: bs251{at}mole.bio.cam.ac.uk

During the development of the Drosophila embryonic epidermis, the secreted Wingless protein initially spreads symmetrically from its source. At later stages, Wingless becomes asymmetrically distributed in a Hedgehog-dependent manner, to control the patterning of the embryonic epidermis. When Wingless is misexpressed in engrailed cells in hedgehog heterozygous mutant embryos, larvae show a dominant phenotype consisting of patches of naked cuticle in denticle belts. This dose-sensitive phenotype is a direct consequence of a change in Wg protein distribution. We used this phenotype to carry out a screen for identifying genes regulating Wingless distribution or transport in the embryonic epidermis. Using a third chromosome deficiency collection, we found several genomic regions that showed a dominant interaction. After using a secondary screen to test for mutants and smaller deficiencies, we identified three interacting genes: dally, notum, and brahma. We confirmed that dally, as well as its homolog dally-like, and notum affect Wingless distribution in the embryonic epidermis, directly or indirectly. Thus, our assay can be used effectively to screen for genes regulating Wingless distribution or transport.